diff --git a/websocket-sharp/Net/HttpListenerContext.cs b/websocket-sharp/Net/HttpListenerContext.cs
index eac93fb5..643465cc 100644
--- a/websocket-sharp/Net/HttpListenerContext.cs
+++ b/websocket-sharp/Net/HttpListenerContext.cs
@@ -240,6 +240,30 @@ namespace WebSocketSharp.Net
       return true;
     }
 
+    internal HttpListenerWebSocketContext GetWebSocketContext (string protocol)
+    {
+      if (_websocketContext != null)
+        return _websocketContext;
+
+      if (protocol != null) {
+        if (protocol.Length == 0) {
+          var msg = "An empty string.";
+
+          throw new ArgumentException (msg, "protocol");
+        }
+
+        if (!protocol.IsToken ()) {
+          var msg = "It contains an invalid character.";
+
+          throw new ArgumentException (msg, "protocol");
+        }
+      }
+
+      _websocketContext = new HttpListenerWebSocketContext (this, protocol);
+
+      return _websocketContext;
+    }
+
     internal bool Register ()
     {
       return _listener.RegisterContext (this);